1. Field of the Invention
The present invention relates to mobile communication technologies.
2. Description of the Related Art
In Long Term Evolution (LTE) systems, uplink control information includes ACKnowledgement/Non-ACKnowledgement (ACK/NACK) of a downlink data packet, a Channel Quality Indicator (CQI), a Rank Indicator (RI) for downlink Multi-input Multi-output (MIMO) feedback, a Precoding Matrix Indicator (PMI) and a Scheduling Request (SR).
FIG. 1A is a schematic diagram illustrating a SR control channel in a mobile communication system according to the related art; and FIG. 1B is a schematic diagram illustrating an uplink ACK/NACK control channel in a mobile communication system according to the related art.
Similar to the structure of the uplink ACK/NACK control channel shown in FIG. 1B, the structure of the uplink SR control channel for transmitting SR information, as shown in FIG. 1A, is a two-dimensional orthogonal channel structure of different circular shifts and time domain orthogonal grouping expansion of a basic Constant Amplitude Zero Auto Correlation (CAZAC) sequence. In the LTE system, fixed SR resources are distributed to each User Equipment (UE) for sending the SR information, and each SR is sent by using a method of On-Off Key (OOK).
In the LTE system, when needing to apply a new uplink resource scheduling, the UE sends a SR a modulation symbol, which is in a SR subframe configured by the UE, so as to request a new uplink data resource. The SR in this case is referred to as a positive SR. When the UE does not have a need for uplink resource scheduling, the SR is not sent on a distributed SR channel. The SR in this case is referred to as a negative SR. In order to ensure a low Constant Modulus (CM) characteristic of uplink signals, it is defined in the LTE system that, if the SR and the ACK/NACK are transmitted in the same sub-frame, for the positive SR, the UE sends the ACK/NACK on the distributed SR channel; and for the negative SR, the UE sends the ACK/NACK on a distributed ACK/NACK channel.
Along with the continuous evolution of the LTE technology, an LTE-Advanced (LTE-A) system has been developed. In the LTE-A system, in order to improve a peak speed rate of the whole system, a method of Carrier Aggregation (CA) is used to implement configurable system bandwidth, and each carrier unit is referred to as a Component Carrier (CC). An LTE UE can work normally at each CC, which is shown in FIG. 2.
FIG. 2 is a schematic diagram illustrating a structure of a radio frame in a mobile communication system according to the related art.
Referring to FIG. 2, a radio frame 210 includes a plurality of subframes 220. A length of the radio frame 210 may be 10 ms, and a length of the subframe 220 may be 1 ms. The subframe 220 consists of a plurality of CCs 230-1 to 230-5 in the frequency domain. A bandwidth of each of the CCs 230-1 to 230-5 may be 20 M, and total bandwidth may be 100 M.
In view of partition of radio spectrum of the related art, in a conference of the 3rd Generation Partnership Project (3GPP) Radio Access Network (RAN) 4 work groups, operators of the LTE-A system propose distributing the CC configured in the LTE-A system into two different frequency bands, which is shown in FIG. 3.
FIG. 3 is a schematic diagram illustrating examples of CC allocations in a mobile communication system according to the related art.
In addition, in order to reduce complexity of LTE-A terminals, it is defined in the LTE-A criterion by the 3GPP RAN 4 that, in a future LTE-A system, when the UE configures multiple downlink and uplink CCs, all the SR and CQI information are sent in the same CC, and downlink data ACK/NACK of different CCs are sent in a certain single CC. Since it is important to ensure the low CM characteristic of the uplink single CC for a receiving capability of uplink control information, there is a technical problem needed to be addressed, which is how to return the SR, ACK/NACK or CQI information to a BS at the same time when uplink CM is minimized. However, in the related art, no method is provided for returning the SR, ACK/NACK or CQI information to the BS when the low CM characteristic of the uplink CC is ensured as much as possible.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.